The invention concerns a device to initial aim or direct an electron beam in a crucible. During heating, melting or evaporation of metallic or other materials, high energy electron beams are often used, which impact onto the material to be heated, melted, or evaporated. Therefore, it is usually required that the electron beam be brought into predetermined positions in order that the attempted purpose be fulfilled.
The effect of electrical or magnetic fields, the change of which causes a change of the position of the electron beam, is utilized for the positioning of a electron beam. It is common to position the beam by means of adjustable currents which in turn build up a deflecting magnetic field. This technique is particularly advantageous. The adjustment is usually manually performed, hereby an operator observes the electron beam through a window and adjusts the currents required for the x position and the y position of the beams by adjusting two potentiometers.
If, within a crucible, several points of the medium are to be sequentially impacted by the electron beam, this type of manual adjustment is very time consuming. This is particularly true if the electron beam is to have different tarrying times at the various positions.
Such different tarrying times are required for specific applications, e.g., if several vapor sources are to be formed on the surface of the contents in one single evaporation crucible such that an electron beam is fired onto the surface of the contents of the crucible in specific surface patterns (DE-OS No. 28 12 285). In order to be able to simply preprogram the power input of the electron beam into a device of such nature, it is already known to represent this power input on a screen in the form of a bar diagram (DE-OS No. 33 30 092), whereby the bars in the bar diagram may be changed by means of a light stylus. However, in this case, the screen is not used for representation of specific coordinates in the plane or in the space.